The present invention relates to a data recording device and a data recording control device. More specifically, the present invention relates to a data recording device and data recording control device that record data while rotating an optical disc at a constant angular velocity.
A compact disc-recordable (CD-R) is known as an optical disc capable of recording data. CD-Rs record data once, for example, in disc units or track units and are superior in their cost efficiency per unit of data.
A pregroove, which is a guide groove, is formed in a spiral configuration in a CD-R. Information such as the position on the disc (i.e., the absolute time) and the respective maker's specifications is written in the pregroove. The pregroove wobbles in accordance with the information in a predetermined manner. When data is recorded in a guide groove, an absolute time in pregroove (ATIP) address that shows the absolute time information on the optical disc is read from the pregroove. Data is then recorded while accurately ascertaining the data recording position on the disc using the ATIP address.
A recording device that records data on a CD-R normally includes:
a recording laser drive circuit for irradiating a laser pulse on an optical disc in accordance with the data being recorded;
a read laser drive circuit for irradiating a laser pulse used to reproduce data on an optical disc and reading an ATIP address in order to find the absolute time in the optical disc; and
a decoder for reading an ATIP address by decoding reflected laser pulse.
Further, in order to irradiate a laser pulse along a pregroove, a recording device is provided with an optical head that adjusts the position of the laser pulse irradiation on the optical disc from the laser drive circuit in the radial direction, and a spindle motor that rotates the optical disc. The recording device irradiates a laser pulse along a pregroove by rotating the optical disc with the spindle motor to move the laser pulse irradiation position in the circumferential direction and by moving the laser pulse irradiation position in the radial direction using the optical head.
Conventionally, the rotation of an optical disc is controlled using the constant linear velocity (CLV) technique. In the CLV technique, the rotation of the optical disc is controlled such that the advancing distance per unit time of the laser pulse irradiated on the optical disc is kept constant. As a result, when data is being recorded, regardless of the recording position on the optical disc, there is no alteration in the write strategy of the intensity, the pulse width and the pulse timing of the laser pulse irradiated on the disc.
However, in order to control the constant linear velocity of an optical disc, the rotating speed of the disc must be slower as the laser pulse irradiation position becomes closer to the radially outer side of the disc. Therefore, the speed of the spindle motor must be altered depending on the position of the laser pulse irradiation on the optical disc. This results in the control of the spindle motor becoming complicated. In particular, if the recording device is installed in a portable computer and driven by a battery, the complicated control of the spindle motor increases the battery power consumption.
Accordingly, the application of a constant angular velocity (CAV) technique to control the rotation of an optical disc is also desired. In this case, however, it becomes difficult to control the recording system of the recording device.
Moreover, recording devices that record data on an optical disc, such as a compact disc-rewritable (CD-RW), or a magneto-optical disc, such as a magneto-optic (MO) disc or a mini disc (MD), also have the same problem. In the specification, unless otherwise stated, the term “optical disc” is understood to include magneto-optical discs.